chore: drop util.styleText to support Node v20+ (#1524)

* chore: drop util.styleText to support Node v20+

util.styleText was added in Node v21.7.0 / v20.12.0. v21.0.0-v21.6.x and
v20.0.0-v20.11.x throw `SyntaxError: ... styleText` at startup because the
import resolves before any user code runs (a real user reported this on
v21.2.0).

OpenCLI is primarily agent-facing — terminal colors are noise to consumers,
and the [OK] / [WARN] / [FAIL] / ℹ / ⚠ / ✖ markers we already write carry
the semantic info that colors only repeated. Strip styleText entirely from
logger / output / doctor / tui / update-check / cli / download/progress /
commands/daemon and clean up the resulting awkward `${'literal'}` template
fragments. engines.node now reads ">=20.0.0".

This removes the Node-version coupling that A/B fixes would only have
papered over.

* fix(runtime): truly support Node v20+ by aligning guard + undici

Follow-up to the styleText removal: declaring engines.node >=20.0.0 is
not enough on its own. Two coupled barriers remained:

- src/runtime-detect.ts: MIN_SUPPORTED_NODE_MAJOR = 21 explicitly
  rejected v20 at startup
- undici@^8.0.2 declares engines.node >=22.19.0; Node 20/21 crash on
  webidl.util.markAsUncloneable before any user code runs

Lower the guard to 20 and downgrade undici to ^6.25.0 (engines >=18.17,
retains Agent / EnvHttpProxyAgent / fetch / Dispatcher). Smoke-tested
--help / doctor / list on Node v20.0.0, v21.2.0, v22.22.2. 213/213
targeted unit tests pass.

Author: jackwener

CHANGELOG.md

@@ -20,6 +20,7 @@
 
 ### Internal
 
+* **runtime** — lower the Node floor to `>=20.0.0`. Three coupled changes: drop all `util.styleText()` usage (added in Node v21.7.0 / v20.12.0; previously crashed v21.0–v21.6 at module load), downgrade `undici` from `^8.0.2` (engines `>=22.19.0`) to `^6.25.0` (engines `>=18.17`, retains `Agent` / `EnvHttpProxyAgent` / `fetch`), and lower `MIN_SUPPORTED_NODE_MAJOR` from 21 to 20 so the startup guard matches the declared `engines.node`. Smoke-tested on v20.0.0 / v21.2.0 / v22.22.2. The colored output (`[OK]` / `[WARN]` / `[FAIL]` / `ℹ` / `⚠` / `✖`) keeps its semantic markers; ANSI colors were redundant for the primarily agent-facing CLI.
 * **extension 1.0.14** — `pageScopedResult` no longer injects `session` into `data`. The field had no consumers and contaminated `exec` results with arbitrary user-JS shapes; routing-relevant identity is already exposed via `Result.page`.
 * **extension 1.0.13** — remove the internal command-session lease-key backdoor.
 

docs/guide/troubleshooting.md

@@ -25,8 +25,7 @@ OPENCLI_CDP_TARGET=detail.1688.com opencli 1688 item 841141931191 -f json
 
 ### Node API errors
 
-- Make sure you are using **Node.js >= 21**. Some features require `node:util` styleText (stable in Node 21+).
-- Run `node --version` to verify.
+- Make sure you are using **Node.js >= 20**. Run `node --version` to verify.
 
 ### Daemon issues